A methodology has been developed for the non-invasive exploration and diagnosis of brain function in children with learning disabilities based upon topographic and statistical analysis of brain electrical activity. These techniques successfully demonstrated functionally significant regional differences in the spectrally analyzed EEG and evoked potential data from 10 year old specifically learning disabled (LD) children (dyslexia-pure). We have confirmed and extended these findings on another population showing that subclasses of dyslexia-pure demonstrate characteristic regional specificity. We have now studied 190 healthy 6 year old kindergarten (KG) boys with this method combined with neuropsychological, motor, and behavioral assessments. We have identified by cluster analysis statistically significant neuropsychological and motor/behavioral subgroupings and have identified unique brain electrical correlates of these subgroups. We are currently restudying these boys in the 2nd grade (2G) to evaluate change over time and develop predictors of 2G outcome(s) from KG data. We propose to follow these boys to grade 4 (4G) where scholastic and linguistic outcome(s) can be assessed in greater detail. We shall investigate development over the K, 2G, and 4G age points to develop predictors of 4G outcome(s) from the KG and 2G points. We shall investigate by serial study the question whether functional problems represent a difference in brain organization or an immaturity in brain development. Furthermore, we propose to extend our study to 120 girls at the KG and 2G age points to identify the specificity of sex - linked brain and behavioral functioning patterns associated with LD. We anticipate our combined neuropsychological, motor, behavioral, school achievement, and neurophysiological measures will improve early and specific detection of LD children, a prerequisite in the optimization of remedial measures, and will expand our basic understanding of the development of brain-behavior relationships.